


Love Live! Demon Slayer!!

by CirclesArePointless



Category: Love Live! School Idol Project, Love Live! Sunshine!!, ラブライブ! 虹ヶ咲学園スクールアイドル同好会 | Love Live! Nijigasaki Gakuen School Idol Doukoukai (Anime), 鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Anime), 鬼滅の刃 | Kimetsu no Yaiba (Manga)
Genre: Action/Adventure, Alternate Universe - Modern Setting, Alternate Universe - No Aqours, Alternate Universe - No μ's | Muse, Crossover, Crossovers & Fandom Fusions, Demon!Kanata Konoe, Demons, Fantasy, Gen, Same Voice Actress, kimetsu no yaiba au, same Seiyuu, yea i'm aware there's a kanata in kimetsu's canon so i gotta clarify
Language: English
Status: In-Progress
Published: 2020-11-18
Updated: 2020-11-18
Packaged: 2021-03-09 20:21:32
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,287
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27621991
Author URL: https://archiveofourown.org/users/CirclesArePointless/pseuds/CirclesArePointless
Summary: Haruka Konoe had been living happily together with her family despite them leading a busy life. Her mother often worked on late-night shifts, while her older sister Kanata had to juggle much of her tasks, more so ever since she got the scholarship to Nijigasaki Academy. The two sisters share a strong bond with each other, they always had each others' back, even if they're school idols from rivaling groups.However, that warmth and happiness was snuffed out one fateful night. Not only was her entire family killed, but it also turned her older sister Kanata into a demon. Haruka vows to avenge her family, and to find a cure to turn her sister back into a human.(Love Live! x Kimetsu no Yaiba fusion AU)
Comments: 4
Kudos: 8





	Love Live! Demon Slayer!!

Since ancient times, demons have been plaguing the nights all across Japan, wreaking havoc against its people. Even in modern times, these unholy creatures actively roam around, be it in the cities or the villages. Fortunately, these demonic threats were not without answers, with rumours abound of a group of demon slayers around the nation helping to keep the night safe. It’s no wonder why people nowadays freely roam outside even in the dead of the night, demon attacks were rarely reported, and most of the population does not even believe of its existence.

It was a cold wintry night in Shinonome, Tokyo, where Haruka Konoe was sleeping peacefully on her bunk bed. However, the same cannot be said for her older sister Kanata, who was still awake even if it’s already an hour past midnight, still busy with her studies. She was always seen as a hardworking person, but sometimes Haruka thought that she can be too hardworking for her own sake, knowing how she had to juggle all her responsibilities as a student, a school idol, a part-time worker, and of course, a caring sister. Meanwhile, their mother was still away on her night shift, supporting the family as much as she could.

Kanata heard the familiar clacking of the front doors, followed by footsteps that certainly belongs to her mother. But what followed seconds after was a sound much different, much violent; it didn’t take long for a feminine scream to shock not just Kanata, but also her sleeping younger sister, who was instantly awaken from her slumber.

“Haruka, call the emergency. Just stay here until they arrive, alright?”

Despite her grogginess, Haruka could sense a tone of urgence from her sister, who immediately tiptoed her way outside, carrying a broom to ward off the assailant.

With not much time to spare, she quickly reached out for her phone, and dialled the emergency number, alerting the operator of a possible robbery in their household. The grating noises continued for a few more minutes; the fact that she had to stay there made her feel very bad, if it were up to her, she would join her sister to fight away this burglar. But alas, the only thing she could do was to trust her sister, and fingers crossed, it will all be fine in the end.

Haruka’s sense of smell had always been sharp, she could identify scents just by sniffing them from a few distance away. It’s what always woke her up whenever her sister made breakfast in the morning; she was blessed not to only have a sister who’s very good at cooking, but also the nose to properly take in all those little details in the aroma.

But tonight, she wished that her nose wasn’t that sharp.

After a few minutes, she could sense an awful smell emanating in the air, and she does not like what it implied. It was pungent yet familiar, and it belonged to none other than her beloved mother and sister.

Eventually, the sirens came into the picture, flashes of red and blue swiftly emanating through the curtains. The struggle seemingly stopped too, Haruka hoped that the entire family made it through, that maybe her nose was tricking her. Moments later, she could hear a knocking at the door, to which she responded by opening it slowly, revealing a police officer on the other side.

But what worried her the most was the expression the officer had, it felt so sorrowful and dejected, as if the only thing the man had in mind was bad news.

“Miss, I regret to inform you that your mother was found dead.”

Those words stung her heart so much, Haruka was immediately overwhelmed by grief over the fate of her family. She shook her head; this can’t be happening! But then, the man in front of her had only mentioned her mother, so that means…

“W-What about my sister?”

“Her body is still warm, and her pulses are still running, and we had called an ambulance to bring her to the hospital.”

For a moment, there was a glimmer of hope in Haruka’s eyes. “Will she make it?”

“I-I can’t make any guarantees…” The officer however was extremely cautious about her chances.

The man then invited her to follow him to the crime scene, and oh dear, what a revolting sight it was. Both her mother and her older sister were lying lifelessly on the floor, their blood splattering almost everywhere. There was no way anyone could’ve survived such an attack; it’s a miracle that they found Kanata still breathing.

Firstly, Haruka rushed towards her mother’s limp body, grasping her mother’s hands while weeping endlessly.

“Mom…”

The daughter was left speechless, it was such a sad sight to see her beloved mother die in the most undignified way possible. Her body was brutally desecrated, and her eyes were devoid of any warmth she had grown to be used to. If anything, it made Haruka tear up more.

“Onee-chan…”

Then, she approached her dear sister’s body. The same could be said for what she was witnessing, but as the officer said, her body was somehow very much alive. She grasped her hands and was relieved from the warmth it exudes. She had no idea how she managed to survive, but at this point, none of that matters. What matters was that her beloved sister is still alive, and she would do anything to keep it that way.

The ambulance arrived shortly after, prioritising the still warm Kanata. Haruka followed suit after asking to come along; she wanted to be on her sister’s side for the rest of the night, and she wants to be there when her sister eventually regains consciousness.

Inside, a nurse was accompanying the two sisters; she was calmly treating Kanata with an oxygen mask to make sure the patient has enough. Her entire body was drenched in blood, but to Haruka’s eyes, it seems as if there was less blood than when she first saw her like this.

As the ambulance sped through the empty streets, the nurse realised how Kanata had almost stopped her bleeding at such a tremendous rate. Meanwhile, Haruka noticed that her sister’s nails were growing sharper, and, wait, a-are those fangs on her mouth?

Kanata woke up violently when she opened her eyes, no longer the familiar friendly shade they were. In fact, it seems far more sinister. Demonic even. She began to growl loudly, distracting the driver who was trying his best to keep the vehicle steady at its current speed.

Her arms were freed effortlessly; they were no match to all the belts that tethered her onto the bed. Kanata suddenly lunged towards her younger sister, puncturing a huge hole on the back of the vehicle, with the driver finally losing control of the ambulance.

Haruka was terribly confused. Just when she thought that things would get better, fate took a sharp turn into the unexpected with what had just happened. She landed hard on the asphalt and took some time before she could steady her vision. Once it was all clear, she could clearly make out her older sister standing still at the distance.

But it was a frightening sight. The Kanata she was seeing was completely different from the Kanata she knew of. Gone was the caring, bright, and hardworking sister she had grown to love.

In its place, was a feral demon ready to devour her in no time.

She remembers all those rumours about man-eating demons, all those stories told by her parents when she was young, the gossips she heard from her friends at school, but never in her life had she thought that these demons very much exist.

And if what she had in mind was right, then she was basically dead meat. It was just a matter of time before her sister’s sharp fangs sink deep into her flesh, ripping it apart piece by piece, and consume her entire being.

But then, Haruka knew her sister very well; Kanata would never hurt her, let alone eat her! It might seem hopeless, but the younger sister could only wish that deep inside her sister, there is still a piece of her humanity left, a piece of warmth and love, anything to combat the growing dark influence inside her. There’s got to be a way to reverse all this!

“Onee-chan!”

Haruka repeatedly pleaded at her sister for mercy, tears still dropping from her eyes. She hoped that her voice would bring some sense back into her precious sister. Her only family member left.

“Hang in there! Be strong!”

She kept on with her pleas, but unfortunately, her sister’s bloodthirst remains. Kanata was slowly walking towards her younger sister, and with each step, she had grown much, much bigger.

“Don’t turn into a demon, please!”

At that moment, Kanata stopped on her tracks completely. Were those tears coming out from her eyes?

Haruka was finally glad that she managed to convince her sister to not cave into her demonic desires. Maybe her condition could be reversible after all! But her joy was short-lived when her sister’s regret quickly turned into a determined rage, and in a split second, Kanata leaped forward with all her newfound might.

This is the end, Haruka thought. She never thought that her caring sister will be the death of her. The poor girl closed her eyes tightly, embracing the inevitable.

Until she heard a deafening crash coming from behind her.

It took Haruka a while to compose herself, and when she turned around, not only was she grateful, but she was touched as well.

Her sister’s love truly never faded away.

Turns out, Kanata had leapt towards a white pickup truck that was coming straight at her younger sister, immediately stopping it full force before it could even touch her beloved sister. Haruka was struck in awe, she knew how her older sister would do anything for her, but stopping a truck with her raw strength? That was something else entirely.

However, when Kanata stopped by to take a look at her precious sister, Haruka saw a mysterious figure leaping towards them, carrying what looked like a weapon. Threatened, the younger girl was quick to her wits and swiftly pushed her sister aside, rolling together away from the streets. They both managed to narrowly avoid the swishing blade, which only grazed a little bit of Haruka’s brown hair. They kept on rolling until they got inside a nearby park, a tree finally stopping their motion.

Who was that?

As Haruka continues to hold on to her sister, she looked towards their assailant, who was standing just a few metres away.

A blue-haired woman was donning a black uniform, with her brown eyes staring back at her coldly. Her right hand was holding a katana, inscribed on it were kanji characters that read out “Destroyer of Demons”.

Could she be one of those fabled demon slayers?

“Why are you protecting it?” The woman’s voice was just as cold as her stare.

“She’s my sister! My older sister!” Haruka exclaimed.

Kanata began to act wild again, letting out angry growls as she tries to escape Haruka’s tight hug. “Onee-chan!”

“You call that thing your sister?”

The woman sped towards them in unbelievable speeds; Haruka could only lie down with her sister held tightly underneath her. After what felt like a gust of wind passing beside her, the girl slowly opened her eyes, only to be shocked by her sister missing from her grip.

Instead, a ravenous Kanata was snatched away by the slayer, tightly holding the demon by her night clothes.

Haruka shouted for her sister, but her pleas went nowhere.

“Don’t move. My job is to slay demons. Needless to say, I’m going to decapitate your sister,” said the demon slayer.

“Wait! My sister hasn’t killed anyone! Someone had attacked our home earlier, that must be the one who killed my family! Not her! I don’t know why she turned into something like that, but…”

The woman quickly stopped Haruka and immediately explained Kanata’s circumstances. Simply put, the reason was that her wounds must have been exposed to demon blood during the attack. After all, that’s how man-eating demons multiply.

Haruka refused to face the fact. There’s no way her sister would ever eat humans!

The blue-haired lady scoffed. “You gotta be kidding. A moment ago, she almost ate you!”

“No! I’m sure she knows who I am! I won’t let her hurt anyone! I’m going to turn my sister back into a human! I’ll find a way to cure her!”

“She can’t be healed. A human who becomes a demon cannot go back.”

The slayer might be hard to convince, but that does not stop Haruka from telling her how she’ll do anything for her sister. “I’ll find a way, no matter what! So, please… please don’t kill her! I’ll hunt down the one who slaughtered my family! I swear! Just, please don’t do it…”

However, the woman ignored all those calls as her blade slowly approached Kanata’s heart.

Haruka repeated her pleas, up to the point where she was bowing down onto the cold ground, begging for the slayer to not take away her sister’s life. She does not want to lose her entire family in a single night.

“Don’t ever give others a chance to murder you!”

Haruka shakily got up when the brown-eyed lady raised her voice.

The demon slayer angrily lectured about how pathetic the younger sister had been acting, doubting that she could even live up to her promises. She reminded her of the harsh reality; all those begging and whining does nothing, how could demons ever respect her if she kept on with that? Haruka’s display of weakness were not worthy of the slayer’s respect either. She even pointed out how she managed to snatch Kanata away, stating that Haruka’s way of protecting her sister was ineffective at best.

Once the lady finished speaking, she pointed her katana straight towards Haruka. There was a hint of regret in her brown eyes, but it didn’t stop her from changing the aim towards Kanata’s heart. When the blade finally pierced Kanata’s skin, Haruka was immediately enraged; how could this woman ever do that to her older sister?

She attacked the slayer with pebbles she found on the ground, running around to attack her from every angle, but all the projectiles were easily dodged by the skilled fighter. She came across a hatchet just beside the park’s storeroom and picked it up but continued to throw pebbles as she was still attacking from the distance. Eventually, Haruka rushed straight towards the slayer, with her arms ready to use the newfound weapon. But her attack was simply snuffed away when the lady used the back of her katana to smack down the girl, leaving her unconscious.

Surprisingly, the girl’s hands were actually free from any weapon, after assuming that her head-on attack would involve the hatchet. But when she looked back up, said hatchet was flying straight towards her head, although she managed to avoid it in time. The slayer had to admit, it was a genius move coming from an inexperienced fighter.

Kanata was enraged by what she had witnessed, so she forced herself out of the lady’s grip and angrily kicked her, sending her body metres away.

The slayer had feared the worst when Kanata rushed towards her younger sister, fearing that the unconscious girl would end up being devoured by her own kin.

But what she saw instead was something unprecedented. Instead of gobbling up the body like any demon would, Kanata instead aggressively stood in front of Haruka, protecting her from any more threats.

Eventually, the demon made her move and rushed towards the slayer, determined to attack whoever that left her sister like that. She swung her arms many times, even trying to kick the lady, but all her efforts were gracefully avoided.

The slayer was still surprised, the fact that the demon didn’t eat up her sister even if she seemed very hungry was a hint that these sisters might be different.

When Kanata was heading towards her after jumping off a tree trunk, the slayer simply hit her neck, knocking her out.

Hours later, Haruka woke up to the sight of her older sister lying beside her, albeit with a gag made of bamboo covering her mouth.

“You awake?” The demon slayer had remained at the scene, catching Haruka off-guard.

“Go see a woman named Nozomi Tojo who lives at the foot of Mount Sagiri. Tell her that Umi Sonoda sent you.”

Umi even advised the young teenager on how to take care of her older sister, the core point being to guard her from sunlight. They were lucky that it was still the early morning right now.

After that, the lady immediately disappeared, leaving the Konoe sisters alone in the park.

\----

“Has anyone seen Kanata?”

“Can somebody try call her?”

“Is she oversleeping again?”

These questions had been bouncing off repeatedly inside the clubroom for Nijigasaki’s school idol club, where its members had grown more concerned over their fellow member’s absence. Several minutes have passed since their supposed start time for their meeting, but with no concrete response from any of the girls, they were unsure if they should just start today’s session without her, or that they should wait a little more.

The problem is, this kind of absence was quite uncharacteristic for the third-year student. If anything, it felt more like a disappearance. If Kanata were to be absent the whole day, she would’ve told someone; and if she really had overslept, which had happened several times, a simple phone call should suffice.

But with no news from any of them, nor her classmates that they knew of, the situation began to unsettle the club members. Even Kanata herself was uncontactable, all the phone calls they made were left unanswered and went straight into the voicemail. It was terribly frustrating. They even tried calling her younger sister, Haruka, but were met with the same automated voice instead.

While they were understandably worried, the girls knew they couldn’t just delay the planned meeting, especially with all the other plans they would have ahead.

But before Setsuna could even open her mouth, a loud knocking was heard on their door. Could it finally be Kanata herself?

The student council president quickly rushed towards the source, and gently opened the door.

Instead of their friend though, it was her younger sister that stood in front of her. Haruka was panting endlessly, looking very exhausted. Behind her back was a large backpack, Setsuna could imagine how tiring it can be to carry something like that around in a school this huge.

Setsuna kindly gestured at her to come inside and to take a seat at the cushioned sofa, giving her all the space needed to relax. Haruka heaved out a sigh of relief once she laid herself over the cushions and started to explain herself.

“I’m sorry that I got here late, the clubroom’s quite far away from the main entrance…”

The rest were all ears, curious about her visit. A worried Shizuku began to ask her a question. “So, what brings you here? Do you know what happened to Kanata?”

Haruka replied rather hesitantly. “Well, about that… Can someone close the curtains, please?”

Yuu and Ayumu complied with her request, pulling down the curtains on all the clubroom’s windows. Kasumi even helped out by turning on the lights.

Haruka then gently unzipped the bag, placing it on the floor. The zipper was already slightly open before she did so, as if there was a living, breathing creature inside. The bag was then carefully rested down on the ground once it was opened wide enough.

“Onee-chan?”

“Huh?”

The muffled sleepy voice shook the entire room. That certainly is Kanata’s voice alright, but why did it came from the backpack?

Slowly, the bag began to move on its own, its content crawling its way outside. And when it did come out, the entire room was coloured surprised by what they were witnessing.

It really was Kanata, only that her body was oddly as small as a little child.

It didn’t take long for her figure to grow back to its normal size though, which again, was met with awe and disbelief.

Aside that, the girls had also noticed some changes to Kanata’s body. Her mouth was occupied by a bamboo muzzle, neatly secured around her jaw. Her hair was still the familiar light brown shade it was, except that it got darker on the edges, much like Yuu’s black hair with its green edges.

However, once Kanata stood up on her two feet, fear quickly filled the clubroom’s atmosphere when the rest of the girls saw her face. A face filled with bloodlust. Kanata began to act very violently, followed by high-pitched screams replacing the silence.

“Onee-chan! They’re your friends!”

Haruka kept the situation under control by holding tightly onto Kanata, making sure that her older sister does not end up hurting anyone. Her voice had successfully snapped Kanata out of her rage, who then began humming a melody from one of her songs, with an added questioning intonation. The other members of the club were relieved, but they were now all focused on the single most important question of the day.

“W-What happened to her?”

Haruka started to tear up. “Last night, we got a-attacked…” She was struggling to hold back her tears as she continued describing last night’s situation. “Onee-chan told me to stay at my bed and call the emergency, and then she went outside to check out what’s going on. But when the cops came, t-they told me that they found both my mother’s and my sister’s body lying lifelessly there…”

Shizuku slowly approached the little girl, comforting her with a warm hug.

“We’re sorry to hear that…”

Meanwhile, the attention shifted towards Emma, who was stroking Kanata’s hair when the sleepy girl’s head rested on her lap. “Then, h-how did she survive?”

“Well…” Haruka was contemplating in her mind on how to approach this matter, considering how unreal it was. Sure, they had witnessed how feral her sister can be nowadays but leaving them in the dark is not a good idea.

“Onee-chan became a demon.”

Amidst the shock, she began to explain how her sister ended up being one, and how a demon slayer had almost killed her. Some information, such as the slayer’s identity, were omitted of course; even Haruka herself was not sure if she was supposed to tell them about all this.

The club members were stunned by her account; not only were those legends real, but it had also affected a fellow friend, and the future of her life. They couldn’t imagine the anguish Haruka must be facing currently. To see a talented school idol wasting away her potential is nothing compared to seeing a loving and caring older sister turned into a wild, feral beast.

“So, what are you gonna do next?” Ai asked.

“I’m gonna find a way to cure my sister. That’s why I came here to tell you all this. It might take weeks, months, or maybe even years, and I don’t want you guys to worry if we disappear for a long time. I’ve already told my friends back in Shinonome Academy about this, so on behalf of my sister, I’m announcing her indefinite leave from Nijigaku.”

“Do what you must,” said Setsuna, her calm words representing the general mood from the rest of the members.

The girls were understandably supportive, it was a tough decision to make, especially with how this situation is jeopardising their future. Besides, how can someone be a school idol if sunlight burns them off, and in Kanata’s case, singing with a gagged mouth?

Although, without a definite timeframe, they fear that the sisters would take quite a while before they could find a way to make Kanata human again, if there were any. But then, it was a better option than letting Kanata to stay as a demon and end up devouring them all when she could no longer control her hunger.

With that being said, the club bid their heartfelt farewell to the sisters, each of the girls taking turns to individually hug Kanata. They gave her some words of encouragement, wishing them luck and reassuring her that she won’t be forgotten, and that they will always be by her side.

“I’ll miss seeing you around…”

“Whenever you get back, you’re free to use my lap as a pillow like always!”

“Rina-chan board: Do your best!”

“Will you keep contact with us?” Yuu asked, being the last person to hug the girl.

If it were up to Haruka, she would message them at least every day. But she knew how the mountains might not have sufficient mobile coverage, so a consistent communication would be unlikely. “I can’t guarantee, but I’ll try my best! Don’t worry, we will always remember you all!”

“We won’t forget you too!” The entire club beamed with a reassuring smile. Sure, this might have disrupted their relatively peaceful lives; after all, they were about to lose a close friend for what could possibly be a long time! But if it’s for her best, then what else could they do?

Haruka then asked Kanata to get back inside her backpack. The older sister made her body smaller in front of her friends, who were still in awe by what they had seen. The girls exchanged one more goodbye before Haruka stepped out of the clubroom, beginning her new adventure.

**Author's Note:**

> oh dear, y'all have no idea how long i've been keeping this idea in my head. not only do both kanata (love live) and nezuko share the same seiyuu, but they're also sleepyheads...
> 
> been meaning to start writing when i had at least finish the manga (kimetsu no yaiba) but then kanata's episode (love live nijigasaki) came and i felt the sudden urge to at least write a pilot of this.
> 
> so, it might take a while before the next chapter comes out, because first, i wanna finish the manga, and second, i'm still figuring out the characters (some characters might stay, but some might be replaced by the girls from love live SIP/sunshine which i felt suitable, like you've seen in this chapter earlier). so, i'm really sorry if i kept you waiting.
> 
> (also, kanata's episode made me sob)


End file.
